Infliximab, a monoclonal antibody against tumor necrosis factor alpha (TNF-α), is approved in Europe for the treatment of patients with active ankylosing spondylitis (AS) who have responded inadequately to conventional therapy. This report provides analyses from a 3-year extension study, as a follow-up to both the 1-year and 2-year open label extensions of the original 3-month randomized controlled trial of infliximab in patients with AS.

Of the 49 patients with AS who completed the second year of the study, 46 continued treatment with infliximab 5 mg/kg every 6 weeks through week 156. The Bath AS Disease Activity Index (BASDAI), the Bath AS Functional Index, the Bath AS Metrology Index, patient's and physician's global assessment, quality of life (Short Form-36), C-reactive protein, and erythrocyte sedimentation rate were assessed throughout the study period.

The improvement of signs and symptoms observed in the majority of the patients during the first and second year was sustained throughout the third year of the study. Forty-three patients (62% of the 69 patients enrolled at baseline and 93% of the patients who started the third year) completed week 156. A BASDAI 50% improvement was achieved by 28 of 43 patients (65%) at week 156. The scores for other efficacy assessments were similar to the values observed at weeks 54 and 102. Median C-reactive protein levels remained low (1.5 mg/l at week 156). There were no relevant side effects and no discontinuation because of drug-related adverse events during the third year of the study.

Patients with AS receiving infliximab for 3 years showed durable clinical response without loss of efficacy. Long-term infliximab treatment was well tolerated by patients in this study.